Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2006-74332 “Multiplex Transmission Apparatus and Method”) discloses a method for performing a statistical multiplexing control in a real-time encoder. According to this method, however, it is necessary to delay a video until completion of the statistical multiplexing control by using a two-pass real-time encoder including a delay circuit so as to follow a steep change in an image feature value.
Further, in the case of performing the statistical multiplexing control without delaying a video, a system configuration as shown in FIG. 3 is employed. FIG. 3 is a system configuration diagram showing a system configuration of a video encoding system of a related art. A video encoding system shown in FIG. 3 includes a program bank device 10A, a delivery encoder group 20A, a TS-MUX 30, and a statistical multiplexing controller 40A, and operates in cooperation with a program operation management server 50.
Program video/voice information is recorded in a first program VTR 1a, a second program VTR 1b, a third program VTR 1c, . . . , and an n-th program VTR 1n, for example, for each program. These pieces of information are respectively compression-coded by a first encoder 11Aa, a second encoder 11Ab, a third encoder 11Ac, . . . , and an n-th encoder 11An of the program bank device 10A, and are accumulated in a program database 12A of the program bank device 10A. Note that in FIG. 3, the terms “first xx”, “third xx”, “second xx”, and “n-th xx” of the first program VTR 1a, the second program VTR 1b, the third program VTR 1c, . . . , and the n-th program VTR 1n, the first encoder 11Aa, the second encoder 11Ab, the third encoder 11Ac, . . . , and the n-th encoder 11An, and the like are represented as “xx1”, “xx2”, “xx3”, . . . , and “xxn” so as to simplify the illustration (the same is applied to the other terms).
In this case, program operation information 51 is input from the program operation management server 50 that operates in cooperation. Then, the corresponding program video/voice data is retrieved from the program database 12A, and is decoded by a first decoder 13a, a second decoder 13b, a third decoder 13c, . . . , and an n-th decoder 13n. Decoded signals are output to the delivery encoder group 20A as a first video/voice 14a, a second video/voice 14b, a third video/voice 14c, . . . , and an n-th video/voice 14n. The delivery encoder group 20A includes a first delivery encoder 20Aa, a second delivery encoder 20Ab, a third delivery encoder 20Ac, . . . , and an n-th delivery encoder 20An.
In the delivery encoder group 20A, upon receiving the videos/voices 14a, 14b, 14c, . . . , and 14n, the delivery encoders analyze a first image feature value 22a, a second image feature value 22b, a third image feature value 22c, . . . , and an n-th image feature value 22n, respectively. The first image feature value 22a, the second image feature value 22b, the third image feature value 22c, . . . , and the n-th image feature value 22n are fed back to the statistical multiplexing controller 40A. The first image feature value 22a, the second image feature value 22b, the third image feature value 22c, . . . , and the n-th image feature value 22n are necessary for encoding data into a state compatible with a transport stream (TS) format of each of a first TS 21a, a second TS 21b, a third TS 21c, . . . , and an n-th TS 21n. 
The statistical multiplexing controller 40A refers to program operation information 52 supplied from the program operation management server 50. Further, the statistical multiplexing controller 40A performs statistical multiplexing analysis processing using the image feature values fed back from the respective delivery encoders of the delivery encoder group 20A. Through the processing, a first video encoding bit rate 41Aa, a second video encoding bit rate 41Ab, a third video encoding bit rate 41Ac, . . . , and an n-th video encoding bit rate 41An, which are suitable for encoding each video data, are obtained. The first video encoding bit rate 41Aa, the second video encoding bit rate 41Ab, the third video encoding bit rate 41Ac, . . . , and the n-th video encoding bit rate 41An are respectively output to the first delivery encoder 20Aa, the second delivery encoder 20Ab, the third delivery encoder 20Ac, . . . , and the n-th delivery encoder 20An.
By executing the feedback control as described above, the first delivery encoder 20Aa, the second delivery encoder 20Ab, the third delivery encoder 20Ac, . . . , and the n-th delivery encoder 20An respectively obtain the first video encoding bit rate 41Aa, the second video encoding bit rate 41Ab, the third video encoding bit rate 41Ac, and the n-th video encoding bit rate 41An from the statistical multiplexing controller 40A. The first delivery encoder 20Aa, the second delivery encoder 20Ab, the third delivery encoder 20Ac, . . . , and the n-th delivery encoder 20An encode the first video/voice 14a, the second video/voice 14b, the third video/voice 14c, . . . , and the n-th video/voice 14n, respectively, at an appropriate bit rate. As a result, the first TS 21a, the second TS 21b, the third TS 21c, . . . , and the n-th TS 21n can be generated without degrading the video quality. The first TS 21a, the second TS 21b, the third TS 21c, . . . , and the n-th TS 21n are each output to the TS-MUX 30.
The TS-MUX 30 multiplexes the received first TS 21a, second TS 21b, third TS 21c, . . . , and n-th TS 21n and outputs them as a transport stream TSm.
As described above, in the video encoding system shown in FIG. 3, the image feature values (the first image feature value 22a, the second image feature value 22b, the third image feature value 22c, . . . , and the n-th image feature value 22n), which are obtained after video encoding and analyzed in the first delivery encoder 20Aa, the second delivery encoder 20Ab, the third delivery encoder 20Ac, . . . , and the n-th delivery encoder 20An of the delivery encoder group 20A, are notified to the statistical multiplexing controller 40A. Further, the statistical multiplexing controller 40A performs the statistical multiplexing control for calculating the bit rates (the first video encoding bit rate 41Aa, the second video encoding bit rate 41Ab, the third video encoding bit rate 41Ac, . . . , and the n-th video encoding bit rate 41An) to be allocated to each of the first delivery encoder 20Aa, the second delivery encoder 20Ab, the third delivery encoder 20Ac, . . . , and the n-th delivery encoder 20An. To accomplish such operations, it is necessary to employ a feedback type control.
In this case, a steep change may occur in the image feature values relating to the first video/voice 14a, the second video/voice 14b, the third video/voice 14c, . . . , and the n-th video/voice 14n. In such a case, it is difficult to allow the bit rate control for allocating bit rates to the delivery encoders 20Aa, 20Ab, 20Ac, and 20An to follow the real-time video encoding timing in each delivery encoder.